Question

我想找到当周的记录数。我目前的疑问是：

SELECT Week(Str_to_date(products_options_values, '%m-%d-%Y'), 1) AS order_week,
       Year(Str_to_date(products_options_values, '%m-%d-%Y')) AS order_year,
       order_active,
       Count(op.sub_order_id) AS deliveries
FROM   orders_products_attributes opa
       LEFT JOIN orders_products op
              ON ( opa.orders_products_id = op.orders_products_id )
GROUP  BY order_week,
          order_year
HAVING order_week = '31'
       AND order_year >= '2013'
       AND order_active = 0
ORDER  BY order_week

它获取deliveries AS 2，其中实际上有4条记录，如果我在删除COUNT和GROUP BY后运行相同的查询，则会正确显示所有4条记录行。其他周也会出现同样的问题，例如第34周有3条记录，但上面的查询却将其取为4。此外，另一个奇怪的事情是，在GROUP BY子句中，如果我删除order_week或order_year中的任何一个，查询将返回一个空结果集。

知道我做错了吗？

Answer 1

尝试将所有HAVING条件移至WHERE。另外Count(id) - 计算ID的UNIQUE值并非全部。如果您需要所有记录计数，请使用COUNT(*)

SELECT Week(Str_to_date(products_options_values, '%m-%d-%Y'), 1) AS order_week,
       Year(Str_to_date(products_options_values, '%m-%d-%Y')) AS order_year,
       order_active,
       Count(op.sub_order_id) AS deliveries
FROM   orders_products_attributes opa
       LEFT JOIN orders_products op
              ON ( opa.orders_products_id = op.orders_products_id )
WHERE order_week = '31'
       AND order_year >= '2013'
       AND order_active = 0

GROUP  BY order_week,
          order_year
ORDER  BY order_week

Mysql count（）获取错误的结果

1 个答案: